An ink-jet printer produces images and text on a page by firing drops of ink from the printheads of one or more ink cartridges secured to a carriage, while the carriage moves back and forth across the page. Examples of ink-jet printers include plotters, facsimile machines, and typical computer-attached inkjet printers. The page on which a printer prints may be any sheet of material, such as paper, Mylar, foils, transparencies, card stock, etc.
The ink supply of an ink-jet printer is limited. Thus, many cartridges are designed to be detachably secured and replaceable. A user simply replaces the old, empty ink cartridge with a new, full ink cartridge. In these so-called cartridge-type printers, the cartridges can be manufactured as a unit that includes a printhead and an ink reservoir (referred to as an “ink/printhead cartridge” herein). Thus, these types of ink/printhead cartridges are seated in a carriage that travels back and forth across the page during printing operation.
Since traditional ink/printhead cartridges each include an ink reservoir, an integral printhead, and the related electronics to operate the printhead, they are relatively expensive to manufacture and replace. These types of cartridges are typically sealed and do not allow individual components within them to be replaced. Accordingly, if either the printhead becomes inoperative or the ink supply becomes depleted, the entire cartridge must be replaced. As a result, the cost to operate and maintain such printers in necessarily increased.
Alternatively, in some designs commonly known as off-axis printers, the ink reservoir is a container that may be disconnected from the printhead, which remains installed on the carriage while the container is replaced. In the typical off-axis printer, only a printhead moves across the page, while the ink reservoir is stationary and secured to the base of the printer. Ink is delivered to an inlet port in the printhead via a flexible, ink delivery tube that extends from the stationary ink reservoir and usually requires a separate pump to deliver the ink. Typically, the ink reservoir is mounted to the printer chassis and may be replaced or refilled when empty. Off-axis printers may be equipped either with a single printhead for monochromatic printing, or with several printheads for color printing. Of course, for color printing, several reservoirs and associated tubes are required, with one set used for each color.
In the ink-delivery systems of off-axis printers, the ink-delivery tube may be permanently connected to the printhead, but this would prevent replacement of the printhead. The printhead may suffer mechanical breakdown or simply wear-out after firing millions of drops of ink. Therefore, the printheads of a typical ink-jet printer are designed to be replaced, as necessary. Similarly, the supply of ink in reservoirs or containers used in cartridge-type or off-axis type printers may be replenished in refill stations that are peripheral components of the printer system.
In practice, the expense associated with providing ink-delivery tubes and related delivery pumps necessarily increases the costs of manufacturing such printers. Moreover, forces generated by these types of ink-delivery systems can vary as the carriage traverses the paper. These varying forces can adversely affect carriage operation, including leading to premature wear of the carriage and compromised print quality.
With limited success, some inkjet printer designs have incorporated an ink reservoir and a separate printhead on the carriage, thereby avoiding the need for an off-axis ink delivery tube system. However, the placement and orientation of components for these designs has typically either compromised the ability to easily remove and replace the printhead, or required that the ink reservoir be removed before the printhead can be accessed. In designs where the ink reservoir must be removed either before or simultaneously with the removal of the printhead, the risk of loss or premature drying of the ink reservoir is increased.